DUAL ZONE BUS BAR ARRANGEMENT FOR HEATABLE VEHICLE
WINDOW
This invention relates to a bus bar arrangement for a heatable vehicle window
(e.g., vehicle windshield) including at least first and second heating zones. In
particular, this invention relates to a bus bar arrangement including first and second
spaced apart top bus bar portions which work in conjunction with a bottom bus bar to
define at least first and second heating zones on a vehicle window.
BACKGROUND OF THE INVENTION
Heatable windows are known in the art. For example, see U.S. Patent Nos.
5,434,384 and 4,782,216, the disclosures of which are hereby incorporated herein by
reference. Heatable windows conventionally include first and second conductive bus
bars in electrical contact with a transparent conductive coating including an
electroconductive layer. The electroconductive layer generates heat when electric
current is passed therethrough. In such a manner, snow and ice may be melted from
vehicle windows such as windshields, backlites, sidelites, and/or the like. Windows
may also be defogged in such a manner.
In conventional heatable windows, first and second bus bars are often located in
spaced apart relation proximate opposite edges of the window. Unfortunately, this type
of design often requires the electrical connector for the top bus bar to exit the window
at the top edge thereof, and the electrical connector for the bottom bus bar to exit the
window at the bottom edge thereof. This is undesirable in that it is much more
convenient if both connectors (i.e., for both bus bars) are located along the same
edge/side of the window.
In an attempt to overcome the aforesaid problem, U. S. Patent No. 4,820,902
discloses first and second conductive leads/extensions arranged from opposite sides of
the top bus bar heading down the respective sides of the windshield and across the
bottom side/edge of the same. In such a manner it is possible to locate the electrical
connectors for both bus bars at the bottom edge/side of the windshield. Unfortunately,
the design of the '902 patent is undesirable in that the entire viewing zone of the
windshield is heated via a single heating zone.
It will be apparent to those skilled in the art that there exists a need for a more
efficient multi-zone bus bar arrangement for a vehicle window.
SUMMARY OF THE INVENTION
An object of this invention is to provide an efficient bus bar arrangement for a
heatable vehicle window (e.g., windshield).
Another object of this invention is to provide a bus bar arrangement for a
heatable vehicle window, wherein the bus bar arrangement defines at least first and
second heating zones.
Another object of this invention is to fulfill one or more of the above-listed
objects.
Generally speaking, certain example embodiments of this invention fulfill one or
more of the above-listed needs by providing a heatable vehicle windshield including a
top edge, a bottom edge, and first and second side edges, the heatable vehicle
windshield comprising:
first and second glass substrates laminated to one another with at least a polymer
inclusive interlayer therebetween;
a coating located between said first and second substrates, said coating including
at least one conductive layer;
first, second, and third conductive bus bars, wherein at least portions of said
first, second, and third bus bars are in electrical communication with said conductive
layer of said coating, so that when electric current is passed through said conductive
layer via bus bars at least a portion of the windshield is heated;
wherein a top portion of said first bus bar and a top portion of said second bus
bar are located in spaced apart relation at a top area of said windshield, and said third
bus bar is located at a bottom area of said windshield;
wherein a first heating zone is defined by a portion of said coating in electrical
communication with and between (i) said top portion of said first bus bar, and (ii) said
third bus bar, and a second heating zone is defined by a different portion of said coating
in electrical communication with and between (i) said top portion of said second bus
bar, and (ii) said third bus bar; and
wherein connection portions of said first and second bus bars are provided
proximate or adjacent the bottom edge of the windshield so that corresponding
electrical connectors in electrical communication with first, second, and third bus bars,
respectively, are each attached to the windshield proximate the bottom edge thereof, at
least one of said electrical connectors supplying electric current to said conductive layer
of said coating via an external power source.
Certain other embodiments of this invention fulfill one or more of the above-
listed objects by providing a heatable window comprising:
at least one substrate supporting a coating;
first, second, and third conductive bus bars, wherein at least portions of said
first, second, and third bus bars are in electrical communication with a conductive layer
of said coating, so that when electric current is passed through said conductive layer via
bus bars at least a portion of the window is heated;
wherein a first portion of said first bus bar and a first portion of said second bus
bar are located in spaced apart relation from one another at a top or upper area of said
window, and said third bus bar is at least partially located at a bottom area of said
window;
a first heating zone defined by a first portion of said coating in electrical
communication with and between a) said first portion of said first bus bar, and b) said
third bus bar;
a second heating zone defined by a second portion of said coating in electrical
communication with and between a) said first portion of said second bus bar, and b)
said third bus bar; and
wherein connection portions of said first and second bus bars are provided
proximate or adjacent a bottom edge of the window so that corresponding electrical
connectors in electrical communication with the first, second, and third bus bars,
respectively, are each attached to the window proximate the bottom edge thereof, at
least one of said electrical connectors supplying electric current to said conductive layer
of said coating via an external power source.
Still further embodiments of this invention fulfill one or more of the above-listed
needs by providing a heatable window comprising:
at least one substrate supporting a heatable conductive layer;
first, second, and third spaced apart bus bars each in electrical communication
with said heatable conductive layer;
a first heating zone including a first portion of said conductive layer defined
between a top or upper portion of said first bus bar and said third bus bar;
a second heating zone including a different second portion of said conductive
layer defined between a top or upper portion of said second bus bar and said third bus
bar; and
wherein said top or upper portions of said first and second bus bars, respectively,
are located in spaced relation from one another at a top or upper area of said window,
and said third bus bar is located at a bottom area of said window.
This invention will now be described with respect to certain example
embodiments thereof as illustrated in the following drawings, wherein:
IN THE DRAWINGS
Figure 1 is a top plan view of a heatable vehicle windshield according to an
exemplary embodiment of this invention (absent opaque shielding layers for purposes
of illustration simplicity).
Figure 2 is a side cross sectional view of a multi-layer coating provided on one
of the substrates of the vehicle windshield of Fig. 1, with a pair of silver (Ag) frit
inclusive bus bars deposited on the substrate over the coating, during the process of
manufacturing the windshield of Fig. 1 (at section line 4 - 4 shown in Fig. 1).
Figure 3 is a side cross sectional view of the bus bars and coating of Fig. 2, after
and/or during heating which causes at least a portion of the bus bars to bleed through at
least one dielectric layer of the coating and come into contact with at least one of the
electroconductive silver (Ag) layers of the coating thereby establishing an electrical
connection with the same.
Figure 4 is a side cross sectional view of the vehicle window of Fig. 1 (taken
along Section Line 4 - 4 in Fig. 1), after the Fig. 3 structure has been laminated to
another glass or plastic substrate with a polymer (e.g., PVB) interlayer provided
therebetween to complete a vehicle windshield or other vehicle window.
Figure 5 is a top plan view of a heatable vehicle windshield according to another
exemplary embodiment of this invention (absent opaque shielding layers for purposes
of illustration simplicity).
Figure 6 is a top plan view of a heatable vehicle windshield according to another
exemplary embodiment of this invention (absent opaque shielding layers for purposes
of illustration simplicity).
DETAILED DESCRIPTION OF CERTAIN EXEMPLARY EMBODIMENTS OF THE INVENTION
Referring now more particularly to the accompanying drawings in which like
reference numerals indicate like parts or layers throughout the several views.
Certain embodiments of this invention relate to a bus bar arrangement for a
heatable vehicle window (e.g., windshield). First and second spaced apart elongated
conductive top bus bar portions, and an elongated conductive bottom bus bar, are
provided. Each bus bar is in electrical contact or communication with at least one
electroconductive layer(s) of a coating (e.g., low-E coating) deposited on the window.
Each top bus bar has one free end, and another end from which a conductive extension
protrudes. The extension from each top bus bar leads from a location proximate the top
side/edge of the windshield down along a side edge thereof to the bottom side/edge of
the window. In such a manner, electrical connections or connectors for (i) both top bus
bar portions, and (ii) the bottom bus bar, may all be provided along the same side/edge
(e.g., along or adjacent the bottom edge) of the window (e.g., windshield). Moreover, a
dual zone heating system may be provided using the two top bus bars in conjunction
with the bottom bus bar.
Figure 1 illustrates an example embodiment of this invention (opaque shielding
layers are omitted from Fig. 1 for purposes of illustration simplicity). Referring to Figs.
1 and 4, the vehicle windshield includes a multi-layer low-E coating 3 sandwiched
between first and second glass substrates 2 and 4, respectively. Coating 3 is at least
partially deleted (see deletion lines 12) in order to divide the coating 3 into a right-hand
heatable coating portion 3a and a left-hand heatable coating portion 3b. Portions 3a and
3b of the coating are spaced apart from one another (i.e., see insulating area 4 between
the coating portions 3a and 3b, this insulating area being formed by deletion 12 near the
central area of the window), and optionally may be electrically insulated from one
another. For purposes of example only, it is noted that insulating area 4 can be formed
in the shape of a fine line (e.g., providing a gap of about 0.5 mm or less) using laser
deletion techniques. A polyvinyl butyral (PVB) interlayer 5 is provided between the
substrates for conventional lamination purposes. According to certain embodiments of
this invention, the multi-layer coating 3 is provided on the interior surface of one of
substrates 2, 4, so that the coating is provided on what is known conventionally as the
windshield's #2 or #3 surface. The window or windshield shown in Fig. 1 includes top
side/edge 6a, side edges 6b and 6c, and bottom side/edge 6d. Optionally, rain sensor 21
may be located on the window or windshield in an area free of coating 3.
First, second, and third electroconductive elongated bus bars 7, 8 and 9 are
provided between the substrates 2, 4, so as to be in electrical contact with at least one
electroconductive layer of the multi-layer coating 3. First bus bar 7 includes top bus
bar portion 7a, extension portion 7b provided along or adjacent window edge 6b, and
connection portion 7c provided along or adjacent bottom window edge 6d. Top bus bar
portion 7a of bus bar 7 is in electrical contact/communication with a top portion of
coating portion 3a, while portions 7b and 7c of bus bar 7 are spaced from and
electrically insulated from coating 3 (i.e., coating deletion line 12 illustrates the edge of
the coating in Fig. 1). Bottom bus bar 9 is also in electrical contact communication
with coating portion 3a (i.e., at a bottom portion of portion 3a). When electric current
is passed through the electroconductive layer(s) of the coating portion 3a via bus bars
7a and 9 (using electrical connectors/leads 8), heat is generated by coating portion 3a in
heating zone #1 in order to defog, defrost, and/or melt ice/snow from the vehicle
window. Electrical connections/connectors 8 supply power to the coating 3 via bus
bars from an external power source. An exemplary external power source may be a DC
battery of the vehicle, and is represented by "+" and "-" in Fig. 1.
Second bus bar 8 includes top bus bar portion 8a, extension portion 8b provided
along or adjacent window edge 6c, and connection portion 8c provided along or
adjacent bottom window edge 6d. Top bus bar portion 8a of bus bar 8 is in electrical
contact/communication with a top portion of right-hand coating portion 3b, while
portions 8b and 8c of bus bar 8 are spaced from and electrically insulated from coating
3. Bottom or third bus bar 9 is also in electrical contact communication with coating
portion 3b (i.e., at a bottom area of portion 3b). When electric current is passed through
the electroconductive layer(s) of the coating portion 3b via bus bars 8a and 9 (using
electrical connectors/leads 8), heat is generated by coating portion 3b in heating zone
#2 in order to defog, defrost, and/or melt ice/snow from the vehicle window. Thus, the
heating system shown in Fig. 1 includes at least first and second different heating
zones; the first heating zone #1 including coating portion 3a which receives electric
current via bus bars 7a and 9, and the second heating zone #2 including coating portion
3b which receives electric current via bus bars 8a and 9. In certain embodiments of this
invention, both heating zones are heated simultaneously, while in other embodiments of
this invention the two different heating zones may be selectively heated (i.e., one may
be heated independent of the other, e.g., thereby enabling the driver side of the window
to be defrosted and thereafter the passenger side of the windshield in order to save
power).
Referring in particular to Fig. 1, top bus bar portions 7a and 8a are provided at a
top area of the windshield proximate top edge 6a, and are spaced apart from one
another so as to not be in electrical communication. Meanwhile, bottom bus bar 9 is
provided at a bottom area of the windshield proximate a wiper rest area and bottom
edge 6d. Thus, top and bottom bus bars 7a and 9 (and 8a and 9) are provided at
opposite sides/edges of the windshield. Free ends 7e and 8e of upper bus bar portions
7a and 8a, respectively, terminate proximate coating deletion hne 12 on opposite sides
of optional insulating gap 4 in the coating. Conductive extensions 7b and 8b extend
from the other ends of the respective upper bus bar portions down to a bottom side/edge
of the windshield so that electrical connectors 8 for all three bus bars 7-9 can be located
on one side of the windshield, and preferably in approximately the same area. Portions
of coating 3 proximate the edge(s) of the substrate 2 are deleted (i.e., referred to as edge
deletion) so that extensions 7b and 8b are electrically insulated from coating 3 and bus
bar 9.
Still referring to Fig. 1, portions 7a, 8a are approximately parallel to portions 7c,
8c, respectively, as well as to top edge 6a and bus bar 9. Portions 7b, 8b are
approximately parallel to edges 6b, 6c, respectively, in certain embodiments. Portions
7c, 8c are both approximately parallel to bottom window edge 6d at certain locations.
As shown in Fig. 1, portions 7c, 8c are spaced from and electrically insulated from both
coating 3 and bus bar 9. Likewise, portions 7b, 8b are spaced from and electrically
insulated from side edges 3c of coating 3.
It is noted that conductive bus bar portions 7a-7c and 8a-8c (and/or bus bars 7, 9)
are said to be located "adjacent" or "along" an edge(s) of the windshield, even though
they may (and are preferably) spaced inwardly from the relevant edge(s) of the
windshield at least one or more inches. Thus, when used relative to an edge of the
window or windshield, the words "adjacent" and "along" as used herein mean that at
least a portion of the conductive bus bar portion or bus bar (i.e., any of 7, 8 or 9) is/are
within about six (6) inches of the mentioned edge of the windshield.
Referring to Figs. 2-4, an exemplary method of making the heatable
windshield(s) of Fig. 1 will now be described. The materials illustrated for the various
layers in Figs. 2-4 are for purposes of example only. Initially, float glass (e.g., soda-
lime-silica glass) substrate 2 is provided. Substrate 2 is from about 1.0 to 10.0 mm
thick, more preferably from about 1.6 mm to 4 mm thick. Low-E coating 3 is deposited
on substrate 2. Multi-layer coating 3 includes first dielectric anti-reflection layer 23,
second dielectric haze-reducing layer 25, first lower contact layer 27 (which contacts
layer 29), first electroconductive metallic infrared (IR) reflecting layer 29, first upper
contact layer 31 (which contacts layer 29), third dielectric layer 33 (which may be
deposited in one or multiple steps in different embodiments of this invention), fourth
dielectric layer 35, second lower contact layer 37 (which contacts layer 39), second
electroconductive metallic IR reflecting layer 39, second upper contact layer 41 (which
contacts layer 39), fifth dielectric layer 43, and finally sixth protective dielectric layer
45. The "contact" layers each contact at least one IR reflecting layer. The aforesaid
layers 23-45 make up heat treatable low-E (i.e., low emissivity) coating 3 which is
provided on substrate 2.
In certain embodiments of this invention, first dielectric layer 23 may be of or
include titanium dioxide (TiOx where x is from 1.7 to 2.3, most preferably 2.0), silicon
nitride (SixNy where x/y may be about 0.75 (i.e., Si3N4), or alternatively x/y may be
from about 0.76 to 1.5 in Si-rich embodiments), silicon dioxide (SiOx where x is from
1.7 to 2.3, most preferably about 2.0), niobium oxide (e.g., Nb2O5), SiZrN, tin oxide,
zinc oxide, silicon oxynitride, or any other suitable dielectric material. First dielectric
layer 23 functions as an antireflection layer in certain embodiments of this invention.
Second dielectric layer 25 may function to reduce haze in certain embodiments
of this invention, and is preferably of or includes silicon nitride (e.g., Si3N , or
alternatively silicon-rich silicon nitride SixNy where x/y is from 0.76 to 1.5, more
preferably from 0.85 to 1.2). When sputtering silicon nitride layer(s) herein, a Si target
may be used, or alternatively a target including Si admixed with up to 3-20% by weight
aluminum and/or stainless steel (e.g. SS#316) may be used, with about this amount of
aluminum and/or steel then appearing in the layer(s) so formed. Other materials may
also be used for haze reducing layer 25, including but not limited to SiZrN.
While Si3N may be used for layer 25 (and/or layer 35) in certain embodiments,
it has been found that a silicon rich type of silicon nitride as layer 25 is better at
reducing haze and/or improving mechanical durability in certain embodiments of this
invention. Absent this layer 25 (and/or 35), haze tends to be at least 0.45; whereas with
this layer(s) it is reduced to no greater than 0.4 as discussed herein. In Si-rich silicon
nitride embodiments, layer 25 (and/or layer 35) is of or includes SixNy where x/y is
from 0.76 to 1.5, more preferably from about 0.85 to 1.2. Si3N4 has an index of
refraction "n" of about 2.04, and an extinction coefficient "k" of about 0. Si-rich silicon
nitride according to certain embodiments of this invention may have an index of
refraction of at least about 2.05, more preferably of at least about 2.07, and may be 2.08
(at 550 and/or 632 nm) in exemplary embodiments. Also, Si-rich silicon nitride
according to certain embodiments of this invention may have an extinction coefficient
"k" of at least about 0.001, and more preferably of at least about 0.003. In a first
monolithic example after HT of a Si-rich nitride layer 5 (and/or 15), "n" was 2.099 and
"k" was 0.0034; while in a second monohthic example after HT "n" was 2.168 and "k"
was 0.014. Si-rich silicon nitride, in addition to being better at reducing haze than
Si3N4, has also been found to adhere better to the titanium oxide of layer 23 in example
embodiments. Surprisingly, it has also been found that Si-rich silicon nitride under the
NiCrOx and Ag layers provides a lower sheet resistance (Rs).
Electroconductive (or simply conductive) infrared (IR) reflecting layers 29 and
39 are preferably metallic and conductive, and may be made of or include silver (Ag),
gold, or any other suitable IR reflecting material. However, metallic Ag is the material
of choice for the IR reflecting layers 29 and 39 in certain example embodiments of this
invention. These IR reflecting layers help enable coating 3 to have low-E
characteristics, as well as heatability.
Contact layers 27, 31, 37, and 41 are of or include nickel (Ni) oxide, or a nickel
alloy oxide such as nickel chrome oxide (NiCrOx), in preferred embodiments of this
invention. NiCrOx layers 27, 31, 37, and/or 41 may be fully oxidized in certain
embodiments of this invention (i.e., fully stochiometric), or may be at least about 75%
oxidized in other embodiments of this invention. While NiCrOx is a preferred material
for layers 27, 31, 37 and/or 41, those skilled in the art will recognize that other
materials may instead be used (e.g., oxides of Ni, oxides of Ni alloys, oxides of Cr,
oxides of Cr alloys, NiCrOxNy, or any other suitable material) for one or more of these
layers. It is noted that contact layers 27, 31, 37 and or 41 may or may not be
continuous in different embodiments of this invention.
When layers 27, 31, 37 and/or 41 comprise NiCrOx in certain embodiments, the
Ni and Cr may be provided in different amounts, such as in the form of nichrome by
weight about 80-90% Ni and 10-20% Cr. An exemplary sputtering target for depositing
these layers includes not only SS-316 which consists essentially of 10% Ni and 90%
other ingredients, mainly Fe and Cr, but Haynes 214 alloy as well, which by weight
consists essentially of (as a nominal composition) the following materials which may
also show up in these layers:
Element Weight %
Ni 75.45 Fe 4.00
Cr 16.00
C .04
Al 4.50
Y .01
One or more of contact layers 27, 31, 37, and/or 41 (e.g., of or including
NiCrOx) is/are preferably oxidation graded in certain embodiments of this invention so
that the degree of oxidation in the layer(s) changes throughout the thickness of the
layer(s). For example, one or more of contact layers (27, 31, 37 and/or 41) may be
graded so as to be less oxidized at the contact interface with the immediately adjacent
IR reflecting layer (29 or 39) than at a portion of the contact layer(s) further or
more/most distant from the immediately adjacent IR reflecting layer. It is believed that
oxidation grading of one or more of contact layer(s) enables the low-E coating 3 to
achieve the combination of heat treatability and high visible transmission (which was
not previously achievable using NiCrOx contact layers in a dual silver low-E coating
system.
Still referring to Figure 2, third dielectric layer 33 acts as a coupling layer
between the two halves of the coating 3, and is of or includes tin oxide in certain
embodiments of this invention. However, other dielectric materials may instead be
used for layer 33, including but not limited to silicon nitride, titanium dioxide, niobium
oxide, silicon oxynitride, zinc oxide, or the like. Fourth dielectric layer 35 functions as
a haze reducer in certain embodiments of this invention, and is preferably of or includes
sihcon nitride (e.g., Si3N , or alternatively silicon-rich silicon nitride discussed above).
However, in alternative embodiments of this invention, other materials (e.g., SiZrN)
may instead be used for dielectric layer 35.
Fifth dielectric layer 43 may be of or include tin oxide in certain embodiments of
this invention. However, other dielectric materials may instead be used for layer 43,
including but not limited to silicon nitride, titanium dioxide, niobium oxide, silicon
oxynitride, zinc oxide, or the like. Protective overcoat dielectric layer 45 is provided at
least for durability purposes, and may be of or include silicon nitride (e.g., Si3N4) in
certain embodiments of this invention. However, other dielectric materials may instead
be used for layer 45, including but not limited to titanium dioxide, silicon oxynitride,
tin oxide, zinc oxide, niobium oxide, SiZrN, or the like.
Other layer(s) below or above the illustrated coating 3 may also be provided.
Thus, while the layer system or coating 3 is "on" or "supported by" substrate 2 (directly
or indirectly), other layer(s) may be provided therebetween. Thus, for example, coating
3 of Fig. 2 may be considered "on" and "supported by" the substrate 2 even if other
layer(s) are provided between layer 23 and substrate 2. Moreover, certain layers of
coating 3 may be removed in certain embodiments, while others may be added in other
embodiments of this invention without departing from the overall spirit of certain
embodiments of this invention.
While various thicknesses may be used for the layers of multi-layer coating 3,
exemplary thicknesses and example materials for the respective layers on the glass
substrate 2 are as follows:
Table 1 (Example Materials/Thicknesses for Coating 3)
Layer Preferred Range (A) More Preferred (A) Example (A)
Ti02 (layer 23) 0-400 A 50-250 A 100 A
SixNy (layer 25) 0-400 A 50-250 A 170 A
NiCrOx (layer 27) 5-100 A 10-50 A 18 A
Ag (layer 29) 50-250 A 80-120 A 105 A
NiCrOx (layer 31) 5-100 A 10-50 A 16 A
Sn02 (layer 33) 0-800 A 500-850 A 650 A
SixNy (layer 35) 0-800 A 50-250 A 170 A
NiCrOx (layer 37) 5-100 A 10-50 A 18 A
Ag (layer 39) 50-250 A 80-120 A 105 A
NiCrOx (layer 41) 5-100 A 10-50 A 16 A
Sn02 (layer 43) 0-500 A 100-300 A 150 A
. Si3N4 (layer 45) 0-500 A 100-300 A 250 A
In other example embodiments, dielectric layer 23 may be removed, and/or
layers 23 and 25 may be replaced with a single sihcon nitride layer of either Si3N or of
the Si-rich type of silicon nitride described above.
In certain exemplary embodiments of this invention, coating/layer systems 3
according to example embodiments have the following low-E characteristics
before/after heat treatment (HT) when in monolithic form, as set forth in Table 2:
Table 2: Monolithic Before/After Heat Treatment (HT)
Characteristic General More Preferred Most Preferred
Rs (ohms/sq.)(before HT): <= 10.0 <= 8.0 <= 5.0 Rs (ohms/sq.)(after HT): <= 8.0 <= 6.0 <= 4.0
En (before HT): <= 0.08 <= 0.06 n/a
En (after HT): <= 0.07 <= 0.05 n a
Haze (after HT): <= 0.40 <= 0.30 <= 0.28
An example low-E coating 3 was deposited as follows on substrate 2 using a
Leybold Terra-G six-chamber sputter coating apparatus. Five cathodes were in each
chamber, so there were a total of 30 cathode targets in the sputter coater. Cathode
numbering utilizes the first digit to refer to the coater chamber, and the second digit to
refer to the cathode position in that chamber. For example, cathode # 32 was the
second cathode (second digit) in the third (first digit) sputter chamber. Cathode #s C13,
C14, C23, C62, C31, C32, C62, C64 and C65 were Twin Mag II type cathodes; cathode
# C42 was a dual C-Mag type cathode; and cathode #s C44, C51, and C53 were planar
cathodes. In the sputter coater, layers 27-31 and 37-41 were sputtered onto the
substrate using DC power sputtering, while the other layers were sputtered onto the
substrate using a mid-frequency AC type system. Below, "*" means Al content of
approximately 10%. The line speed was 2.6 meters per minute (m/min.). All gas
flows (e.g., oxygen, argon, nitrogen) are presented in units of mL/ minute. In the below
examples, though not shown in the charts, the oxygen flow was turned off at the sides
of the NiCr targets discussed above in order to oxidation grade the contact layers 31
and 41 so that they were more oxidized further from the Ag layer(s). Volts refers to
cathode volts, and amps (A) refers to cathode amps. "Tr" stands for trim; and trim (Tr)
console, trim (Tr) Mid, and trim (Tr) pump are all measured in mL/minute. Pressure is
measured in mbar x 10°. Trim gas refers to individually adjusted gas flows along the
cathode length to make corrections regarding layer thickness uniformity. The NiCr
targets were approximately 80/20 NiCr. The process is broken into three separate
charts (i.e., Part #s 1-3) because so much information is presented; only the cathode and
target data is provided for all three charts for ease of reference. Both silicon nitride
layers 25 and 35 were Si-rich through their entire thickness(es); as can be seen by the
fact that much more inert argon (Ar) gas than nitrogen gas was used in sputtering these
silicon nitride layers.
Table 3: Coater Setup/Processes for Coating 3
(Part #1)
Cathode Target Volts (V) Power (kW) Ar Flow (mL/min) O2 Flow (mL/min) N^
Flow
#13 Ti 743 73 200 25 80
#14 Ti 703 64 200 35 50
#23 Ti 738 63.5 200 35 50
#42 Si* 456 29.7 225 0 165
#44 NiCr 370 4.3 150 38 0 # #5511 A Agg 4 43322 3 3..22 100 0 0
#53 NiCr 386 4.1 150 48 0
#62 Sn 431 18.3 200 240 100
#31 Sn 477 24.2 200 290 100
#32 Sn 428 24.5 200 300 100 # #4422 S Sii** 4 45533 3 300..22 225 0 165
#44 NiCr 360 4.2 150 38 0
#51 Ag 430 3.2 100 0 0
#53 NiCr 380 4.1 150 48 0
#62 Sn 442 18.4 200 240 100 # #6644 S Sii<* 5 55544 4 400..66 200 0 200
#65 Si* 545 40.3 250 0 200
(Part #2 continued from Part #1 abovef cathode/target in commonl)
Cathode Target Amps (A) Tank Voltage (V) Freq. (kHz) Trim Gas
#13 Ti 128 364 26.7 o2
#14 Ti 125 346 26.7 o2
#23 Ti 110 344 26.5 o2
#42 Si* n/a 230 26.18 N.
#44 NiCr 11.4 0 0 Ar
#51 Ag 7.4 0 0 Ar
#53 NiCr 10.7 0 0 Ar
#62 Sn 45 203 25.03 o2
#31 Sn 61 224 25.6 o2
#32 Sn 60 225 25.64 o2
#42 Si* na 230 26.18 N2
#44 NiCr 11.6 0 0 Ar
#51 Ag 7.4 0 0 Ar
#53 NiCr 10.5 0 0 Ar
#62 Sn 42 208 25.1 C-2
#64 Si* 93.5 264 26.4 N2
#65 Si* 93.5 273 26.2 N?
(Part #3 continued from Parts #1-2 abovef cathode/target in commonl)
Cathode Target Tr Console Tr Mid Tr Pump Pressure Lambda Lambda
active
#13 Ti 7.5 15 7.5 2.79E"UJ 252 True
#14 Ti 12.5 25 12.5 3.03E"03 252 True
#23 Ti 7.5 35 7.5 4.83E-03 252 True
#42 Si* 50 5 ■45 2.18E-03 0 False
#44 NiCr 15 70 15 2.26E-03 0 False
#51 Ag 15 70 15 1.37E-03 0 False
#53 NiCr 15 70 15 2.16E"03 0 False
#62 Sn 15 70 15 2.12E-03 220 True
#31 Sn 15 70 15 2.97E"03 220 True
#32 Sn 15 70 15 3.19E"03 220 True
#42 Si* 50 5 45 2.52E"03 0 False
#44 NiCr 15 70 15 2.30E-03 0 False
#51 Ag 15 70 15 1.44E-03 0 False
#53 NiCr 15 70 15 2.38E ■03 0 False
#62 Sn 15 70 15 2.24E 03 220 True
#64 Si* 20 60 20 2.88E •03 0 False
#65 Si* 20 60 20 3.61E -03 0 False
After the example of coating 3 was sputtered onto substrate 2 in accordance with
the above, it was tested/measured as follows in Table 4 (i.e., in a monolithic state).
Heat treatment (HT) was performed by placing the coated articles into a furnace heated
to about 625 degrees C for about five (5) minutes, for purposes of simulating heat
bending and/or tempering.
Table 4; Coating 3 Properties Before/After Heat Treatment
(HT)fMonolithicl
Characteristic Example of Coating 3
Tvis, 111. A, 2° (before HT): >=70%
Tvis, 111. A, 2° (after HT): >=78%
Rs (ohms/ sq.)(before HT): 4.43
Rs (ohms/ sq.)(after HT): 3.46
EQ (before HT): <=0.06
En (after HT): <=0.05
Haze (after HT): 0.15
Referring to Fig. 4, after coating 3 has been sputtered onto substrate 2, the
coating is deleted at certain areas of the substrate 2 as shown by deletion lines 12. The
coating 3 is deleted in an approximately elongated area extending from top to bottom of
the window (or vice versa) near the center thereof to form electrically insulating gap 4
between coating portions 3a and 3b. The coating 3 is also deleted proximate edges 6a-
6d of the window or windshield, so that for example, bus bar portions 7b, 7c, 8b and 8c
are located in areas where the coating 3 is not present so that these bus bar portions are
electrically insulated from coating 3 and bottom bus bar 9.
Referring to Figs. 1-2, after coating 3 has been deleted from certain areas of
substrate 2 as shown by deletion lines 12 in Fig. 1, bus bars 7, 8 and 9 (e.g., of or
including Ag inclusive frit) are silk screen deposited/printed on substrate 2. The
conductive bus bars 7-9 are deposited on the substrate 2 over coating 3 in areas where
the bus bars are to be in contact with the coating so as to contact the outer coating
surface (e.g., much of bus bar 9 is deposited over the coating, as are bus bar portions 7a
and 8a). For example, see bus bar portion 7a and bus bar 9 in Fig. 2 as deposited on
the substrate 2 over coating 3. However, in areas where coating 3 has been deleted, the
bus bars are deposited directly on the substrate or alternatively on the substrate over an
opaque enamel layer or the like (e.g., see bus bar portion 7c in Fig. 2). After deposition
of the bus bars 7-9, in areas where the bus bars are provided over the coating 3
dielectric layers 43 and 45 of coating 3 are located between the bus bars 7, 9 and the
electroconductive layers 29, 39 of coating 3. Thus, the bus bars are not in electrical
contact with conductive layers 29, 39 at this time (see Fig. 2). In certain embodiments
of this invention, bus bars 7-9 are each from about 2 to 20 μm thick, more preferably
from about 5-15 μm thick, and sometimes about 10 μm thick. Accordingly, bus bars 7-
9 are much thicker than layers of coating 3 as deposited, although the drawings do not
necessarily illustrate this for purposes of simplicity.
Referring to Figs. 2-3, the Fig. 2 structure (with bus bar 9 and portions 7a, 8a on
substrate 2 over coating 3, and extensions 7b, 7c, 8b and 8c directly on substrate 2) is
then heated (e.g., to a temperature of at least 400 degrees C, more preferably from
about 500 to 700 degrees C) for a period of time (e.g., at least one minute, more
preferably from about 3-15 minutes) so that the bus bars become molten or at least
reach a flowable semi-molten state (i.e., the transition/transformation and/or flowable
temperature of bus bars 7-9 may be less than that of layers 29 and 39). In certain
example embodiments, this heating is also used for heat bending the coated article of
Figs. 2-3 into the desired windshield shape in windshield embodiments (i.e., the bus bar
9 and portions 7a, 8a flow into contact with the Ag layers of the coating during the heat
bending process). In alternative embodiments, this heating may be different from any
heat bending.
During this bus bar bleeding heating step (which may or may not be performed
simultaneously with heat bending), it has surprisingly been found that at least portions
of molten or semi-molten bus bars 7a, 8a, and 9 bleed/flow and/or migrate downward
through at least dielectric layers 43 and 45 of coating 3 until coming into contact with
conductive layer(s) 39 and/or 29 of coating 3 as shown in Fig. 3. The portions of bus
bars 7-9 extending below the surface of coating 3 (i.e., below the outer surface of layer
45) may be referred to as the run-off or bleeded portion(s) of the bus bar(s). The bus
bars and/or coating may be heated to an extent such that the bus bars end up contacting
only one conductive layer 39, or alternatively to an extent such that the bus bars end up
contact both conductive layers 29 and 39 of coating 3 though contact holes 58 formed
in coating 3 (the contact holes 58 are formed in at least layers 41, 43 and 45 by the
bleeding downward of the bus bar material). The bleeding of the bus bar 9 and bus bar
portions 7a, 8a may or may not reach substrate 2 in different embodiments of this
invention, depending upon how long and to what temperature the Fig. 2 structure is
heated. In preferred embodiments, after this heating/bleeding step and subsequent
cooling and solidifying of the bus bar 9 and portions 7a, 8a, the newly formed bus bar 9
and bus bar portions 7a, 8a are now in electrical contact with conductive layers 29 and
39 as shown in Fig. 3 while still retaining their presence at the upper surface of coating
3 so that they can be in electrical contact with connectors 8 and/or extensions 7b, 8b.
Because conductive bus bar portions 7b, 7c, 8b and 8c are not over coating 3,
significant bleeding of the same does not occur during this heating step.
Connectors 8 may be attached to the bus bar 9 and/or bus bar portions 7c, 8c at
this point in the process (i.e., before lamination to another substrate). However, in
alternative embodiments of this invention, the connectors 8 may be soldered onto the
bus bars following the autoclave where the coated article of Fig. 3 is laminated to
another substrate 4.
Referring to Figs. 3-4, after formation of the Fig. 3 structure as described above,
the Fig. 3 structure is laminated to another substrate (e.g., glass substrate) 4 via PVB
layer 5 thereby resulting in the heatable windshield of Fig. 4. Optionally, an opaque
enamel layer (e.g., black or dark enamel) 51 may be provided on the interior surface of
substrate 4 adjacent only relevant edge(s) thereof as shown in Fig. 4 in order to shield
one or more of bus bars 7-9 from the view of persons viewing the heatable window
from outside the vehicle. Also, in certain optional embodiments, an opaque enamel
layer (e.g., black or dark enamel) 53 may be provided on the #4 surface of the
windshield or window (i.e., on the outer surface of inner substrate 2) adjacent only
relevant edge(s) thereof as shown in Fig. 4 in order to shield one or more of bus bars 7-
9 from the view of persons viewing the heatable window from the vehicle interior.
Instead of including enamel, layer(s) 51 and or 53 may instead be of or include an
opaque organic material such as a black primer.
Following formation of the Fig. 4 heatable window structure, it may be installed
into a vehicle to complete a vehicle window assembly. When electric current is run
through both conductive layers 29 and 39 of coating 3 via bus bars 7-9 heat is generated
by the coating (i.e., by at least layers 29, 39). This heat may be used to defog the
window, defrost the window, and/or melt snow/ice from the window or wipers therefor.
It is noted that the multi-layer coating 3 of Figs. 2-4 is provided for purposes of
example only, and this invention is not so limited. For example, this invention is also
applicable to coatings having only one electroconductive layer, as well as to coatings
including three or more conductive layers. Different dielectric layers may also be used.
For example in this regard, reference is made to Figs. 1 and 5-6.
In certain example embodiments, vehicle windows according to certain
embodiments of this invention may be characterized as follows in Table 5, though the
invention is not so limited unless the same is recited in the claims.
Table 5: Color/Transmission After HT; Laminated Form
Characteristic General More Preferred
Tvis (111. A, 2 deg.): >= 70% >= 75%
TV1S (111. C, 2 deg.): >= 70% >= 75%
RgY (111. A, C; 2 deg.): <= 11% <= 9%
a*g (111. A, C; 2°): -2.0 to +2.0 -1.0 to +1.0
b*g (111. A, C; 2°): -10.0 to +1.0 -8.0 to -2.0
RfY (111. A, C; 2 deg.): <= 11% <= 9%
a*f (111. A, C; 2°): -3.0 to +1.0 -2.0 to 0.0
b*f (111. A, C; 2°): -5.0 to 0.0 -4.0 to -1.0
Rsoia,: >= 26% >= 28%
Haze: <= 0.4 <= 0.3
■ solar- <= 50 % <= 48 %
Figure 5 illustrates a windshield according to another embodiment of this
invention. The Fig. 5 embodiment is the same as that shown in Fig. 1 and discussed
above, except that toll window 81 (formed by a deletion in coating 3 at the illustrated
area) is located above and/or between the adjacent ends of the top bus bar portions 7a
and 8a. As a result, bus bar portions 7a and 8a are slightly lower down on the
windshield in this Fig. 5 embodiment, although they are still located at an upper or top
area of the windshield well above the windshield's center as in the Fig. 1 embodiment.
Figure 6 illustrates a windshield according to another embodiment of this
invention. The Fig. 6 embodiment is the same as that shown in Fig. 1 and discussed
above, except that in the Fig. 6 embodiment all three connectors 8 are located
proximate a bottom corner of the windshield (while they are all still proximate the
bottom edge of the windshield). This is because bus bar portion 8c has been extended
to run across a substantial portion of the length of the bottom edge of the windshield,
and portions 7c has been removed.
Once given the above disclosure many other features, modifications and
improvements will become apparent to the skilled artisan. For example and without
limitation, certain embodiments of this invention may include a bus bar arrangement
inverted relative to that shown in Fig. 1, so that the single bus bar 9 is at an upper
portion of the window, and the two bus bar portions 7a and 8a are at a lower portion of
the window. Such other features, modifications and improvements are therefore
considered to be a part of this invention, the scope of which is to be determined by the
following claims: